There is never any reason to disassemble the unit, so the questions aren't really relevant.
C'mon Randy, you know us better than that.
When have we ever needed a REASON to disassemble something?
It just being there is reason enough for most of us.
For me personally, the proper question would be "How do I put (insert name of completely functional device here) back together properly WHEN I disassemble it?".
"If" isn't really in the equation.
"Should I disassemble it" never usually occurs to me until AFTER it's been disassembled.
I've been like that since I ripped the giraffe off my jack-in-the-box at about age 3.
It annoyed me that I couldn't figure out how it worked, so I killed it to find out.
That was actually a functional improvement though.
I could chase my sister around the house after that, and SHOOT her with the giraffe.
I think she still visibly cringes when she hears "Pop Goes the Weasel" to this day.